A typical gas turbine engine is comprised of three main sections: a compressor section, a combustor section, and a turbine section. When in a standard operating cycle, the compressor section is used to pressurize air supplied to the combustor section. In the combustor section, a fuel is mixed with the pressurized air from the compressor section and is ignited in order to generate high temperature and high velocity combustion gases. These combustion gases then flow into a multiple stage turbine, where the high temperature gas flows through alternating rows of rotating and stationary gas turbine airfoils. The rows of stationary vanes are typically used to redirect the flow of combustion gases onto a subsequent stage of rotating blades. The turbine section is coupled to the compressor section along a common axial shaft, such that the turbine section drives the compressor section.
The air and hot combustion gases are directed through a turbine section by turbine blades and vanes. These blades and vanes are subject to extremely high operating temperatures, often exceeding the material capability from which the blades and vanes are made. Extreme temperatures can also cause thermal growth in the components, thermal stresses, and can lead to durability shortfall. In order to lower the effective operating temperature, the blades and vanes are cooled, often with air or steam. However, the cooling must occur in an effective way so as to use the cooling fluid efficiently. As a result, an improved cooling design for airfoils in gas turbines that addresses these issues, among others, is needed.